Project Summary/Abstract The long-term objectives of this project are to improve childbirth outcomes by supporting optimal nursing care during labor and birth. Childbirth is a leading reason for hospital admission in the United States, where approximately 4 million annual births occur. There is widespread variation between hospitals in risk-adjusted childbirth quality indicators suggesting ample opportunity for improving maternal and newborn outcomes. Although nursing care is known to be a central component of patient safety and quality, and is associated with patient outcomes, there are no known nurse-sensitive measures for the specialized nursing care provided during labor and birth. Relationships between nurse-sensitive quality indicators, nurse staffing, and patient safety and quality in medical-surgical and critical care hospital settings are well established in the US, Canada, Europe, and Australia. Research on mechanisms through which nurse staffing affects quality have identified missed nursing care (also known as care left undone or nursing care rationing) as an important factor. Missed nursing care has been linked to adverse outcomes and patient satisfaction. In neonatal intensive care nurse staffing has been shown to moderate health disparities in selected quality outcomes. Nursing care during labor and birth differs substantially from nursing care provided to medical-surgical and intensive care patients, yet there are no validated nurse-sensitive measures for perinatal care. No research to date has assessed the extent to which nurse staffing affects childbirth outcomes or quantified the degree to which missed nursing care during labor and birth might affect complications, patient satisfaction, or health disparities. Nurse staffing ratios for labor and birth are based on standards of care and expert opinion, as no outcomes-based evidence exists to support specific perinatal staffing patterns. This cross-sectional study will link nurse-reported measures of staffing and missed care with patient- and hospital-level administrative data and use multivariate regression modeling and econometric techniques to determine relationships between nurse staffing, missed nursing care during labor and birth, and patient outcomes, and to determine whether variations in nurse staffing and missed nursing care may contribute to health disparities in maternal and infant outcomes. The specific aims are to (1) describe variation in nurse staffing and missed nursing care during labor and birth; (2) determine the relationship between nurse staffing, missed nursing care, and patient outcomes, controlling for moderating variables such as hospital characteristics and patient risk factors; and (3) assess whether disparities in maternal and infant birth outcomes are associated with any systematic differences in hospital staffing or missed nursing care for labor and birth. The outcomes of this study will address a critical knowledge gap in understanding relationships between nurse staffing levels during labor and birth, nursing care provided during labor and birth, patient outcomes, and patient safety. This crucial information can guide efforts to make health care safer during labor and improve US childbirth outcomes.